From the viewpoint of space saving, in recent years, there have been widely used, in place of a CRT type display, flat panel displays such as a liquid crystal display, a plasma display, an OLED display, and a field emission display. Further reduction in thickness is demanded for those flat panel displays. In particular, it is required that the OLED display be easily carried by being folded or wound and be usable not only on a flat surface but also on a curved surface. Further, it is not just displays that are required to be usable not only on a flat surface but also on a curved surface. For example, if a solar cell or an OLED lighting device can be formed on a surface of an object having a curved surface, such as a surface of an automobile body, or a roof, a pillar, or an outer wall of a building, the applications of the solar cell or OLED lighting device may expand. Substrates and cover glasses used for those devices are therefore required to have a smaller thickness and to have high flexibility. Further, a glass film having a reduced thickness and high flexibility is also expected to be used for, for example, reduction in the weights of a glass substrate for devices such as a lithium ion battery, a digital signage, a touch panel, electronic paper, and the like, a cover glass for an OLED lighting device, a drug package, and a window sheet glass.
A light-emitting element used for OLED devices such as an OLED display and an OLED lighting device deteriorates in quality through the contact of gasses such as oxygen. Thus, a substrate used for the OLED devices is required to have high gas-barrier property, and hence a glass is expected to use for the substrate. However, the glass substrate is weak in tensile stress unlike a resin film, and hence is low in flexibility. Thus, application of a tensile stress on a surface of the glass substrate by bending the glass substrate tends to lead the breakage of the glass substrate. In order to impart flexibility to the glass substrate, the glass substrate is required to be reduced in thickness as described above. Thus, Patent Literature 1 below proposes a glass film having a thickness of 200 μm or less.
An elongate glass film has the advantage of being able to be packed and transported with being wound in a roll shape, however, it is necessary, in order to prevent the glass film from breaking, to interpose inserting paper between glass films or to affix a resin film which is peelable in the following process to the glass film. For example, Patent Literature 2 proposes a glass-resin laminate in which a peelable resin film is laminated on a glass film.
However, the glass-resin laminate disclosed in Patent Literature 2 has had a problem in that, when the peelable resin film is adhered to one surface of the glass film in a state of a tension being applied to the resin film, the glass film is occasionally warped significantly toward the resin film side, resulting in the occurrence of wrinkles in the resin film, which leads to a self peel-off of the resin film from the glass film. Therefore, it cannot obtain a sufficient effect to prevent the glass film from breaking.